Float switch



Jan. 1,9, 1954 T. R. wlLsoN 2,666,823

FLOAT SWITCH Filed May 1'7, 1952 G\\ IN VEN TOR.

Patented `Ian. 19, 1954 FLOAT SWITCH Ted R. Wilson,l Seattle, Wash., assigno'r to Boeing Airplane' Company,Y Seattle, Wash., a corporationof Delaware Application May. 17, 1952,*seria1 No.` 2885499 sclaim's: (c1. 20o-84) This invention relates to float actuated switches and more particularly concernsa control switchv incorporating a rotatable magnet moved; by motion of a float, along an arccomp'lementary to a curved soft iron armature which is concentricallymounted on a pivot to actuate movable elements that open and close electrical contacts.

lThe purpose of the invention is to provideA a sensitive and positive operating switchwhich can be utilized for the critical control of fuel valve mechanisms installed in airplanes.

An object ci the invention is to maintain the magnet at a substantially uniform level avoiding gravitational eiects as much as possible.

A further object of the invention is to maintain relatively constant the distance between the magnet and the armature avoiding changes in magnetic attraction as much as possible.

lli

The purpose and objects of the invention will Y become more app-arent as the following descrip- Figure l is a sectional view through a portion of a float chamber containing the magnetic float switch mechanism.

Figure 2 is a partial-section perspective view.

More particularly, the invention comprises a oat chamber lll with rods I2 to receive guides I4 for controlling movement of a float I3, a connecting linkage i3 composed of a connecting rod fastened to the loat i3 and pivctally connected to a crank arm Il by pin IS for transmitting float movement to the m-agnet I9 mounted above it von the shaft J between bearing supports 2 I, a curved soit iron armature 22`-pivotally supported concentric with the arc of travel of the rrotatable magnet I9 on the pin 23 held by the bearings 24 bracket 2l with an actuating plunger 28 located Y immediately adjacent the end 29 of the armature 22, for the control of electrical power distributed through the terminals 3|, 32, 33, and utilized to operate valves (not shown) of a fueling system (not shown) In operation the iloat I3 rises with the rising level of liquid in the chamber I0 interconnected with a fuel tank (not shown). The reciprocal motion of the. float I3 is converted to rotary motion of the magnet I9 by the linkage I5. The swinging magnet I9 'causes the armature 22 to pivot about the pin 23 until its end 29 contacts the plunger 2B of the switch 2B.

Figure 1 illustrates the cooperating arrange- 2 ment or" the parts in this contact position wherein the armature end'il is Ipulled by the magnet i9 tipping the opposite end 29 against the switch plunger 2li.

Lowering or the liquid level reverses the movements placing the magnet l@ opposite the armature end 29, releasing the plunger 23.

VThe valves (not shown) are either motor operated or solenoid operated and the motor or solenoid is energized by the `closing of the float actuated switch.

For safety measures additional similar switchv assemblies can be installed in the ioat chamber it to actuate other means to cut oithe fuel supply if one assembly fails.

The electricalcontacts within the switch 26 can be arranged similarly to the standard single pole, double throw switches employing an actuating pin or plunger, or some equivalent of the plunger cculd be employed such as an insulated mounting of a spring supported contact and terminal member on the curved armature to open one 'circuit and close another upon the rotatio ci' the armature,

When necessary, in addition to improving the sensitiveness of the assembly by the suggested modications of standard switches, the swinging magnet I3 could be counter-weighted neutralizing gravitational effects.

The inventive float switch as shown and described meets the requirements of a dependable and sensitive mechanism. The novel assembly maintains a relatively constant space between the swinging magnet I9 and the armature 22 without materially altering the vertical position of the magnet it. This results in an ease ci operation for the magnet mcves comparatively free from changes in gravitational and magnetic forces.

The curved-path design as described and illustr-ated is the practical assembly of the more ideal horizontal-path design which reaches the ultimate in avoiding gravitational eects but presentsv 3 pivotally mounted in the top central portion of the said float chamber, a linkage composed of a crank arm and rod lconnecting the said oat to the said magnet converting the reciprocating motion of the said float to rotary motion of the said magnet, a curved armature pivotally mounted on the arcuate non-magnetic top of the said float chamber immediately above the said magnet and concentric to its path of motion, and a switch mounted on the top of the said chamber having an actuating member located just above the end of the said armature permitting the pivoting armaturel to contact the switch thereby controlling the distribution of electrical power to valve mechanisms.

2. A iioat switch for automatic control of elec trical operated fuel valves comprising a float chamber, an arcuate nommagnetc top on the said float chamber, a float slidably retained in the said chamber, a magnet rotatably mounted in the said chamber, a linkage between the said float and said magnet for transmitting the motion of the said float to the said magnet, a curved armature concentrically and pivotally mounted outside the said chamber on the arcuate nonmagnetic top above the said magnet along its path of circular motion, and a switching means mounted on the said iloat chamber with its actuating member above `and within the pivoting arc of the end of the said armature permitting contact of the armature when the float rises actuating an electrical valve control circuit.

3. A float actuated switch installation in a fluid chamber for the automatic control of electrical operated mechanisms that regulate the flow of fluids in a fluid system, comprising a float chamber, a float slidably retained within the chamber 4 for reciprocal motion as the fluid level changes, a magnet rotatable in a vertical plane mounted within the chamber with its poles formed to complement the arcuate path dened by the poles themselves during oscillation, a connecting linkage between the reciprocal oat and the rotatable magnet converting the reciprocal motion of the float to the rotary motion of the magnet, a nonmagnetic arcuate separator forming part of the fluid chamber immediately above the magnet to accommodate the rotatable poles, an arcuate armature mounted outside the float chamber on the separator closely spaced thereto and formed complementary to the curvature of both the separator and the path traversed by the magnetic poles, a switching means mounted on the Iioat chamber, and electrical contacts on the switching means placed over one end of the arcuate armature within the deecting arc of the armature whereby the movement of the said magnet as the float rises will cause a rotary motion of the armature resulting in the closing of the electrical contacts and the actuation of electrical operated mechanisms that regulate the 110W of liuds in the system.

TED R. WILSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,272,782 Duffy July 16, 1918 2,116,415 Shenton May 3, 1938 2,335,055 Graves et al Nov. 23, 1943 2,405,140 Grimm Aug. 6, 1946 2,495,149 Taylor Jan. 17, 1950 2,577,165 Thorsheim Dec. 4, 1951 

